For seven years, Prime Minister David Cameron thought it was really clever to call UKIP supporters "fruitcakes, loonies and closet racists". Dave first made this comment in 2006 when he was leader of the Opposition and only changed his position in May when UKIP won 25% of the vote in council elections. The penny finally dropped that without the electoral support of all these fruitcakes, the Conservatives would lose the General Election in 2015. The message went out from Central Office to stop attacking UKIP voters.
That is not to say that the Conservatives should not attack UKIP policies or its leader - just as they would not be expected to hold back on attacking Labour policies and the Labour leader. That is the nature of politics.
So it is quite a surprise that Mr Cameron has failed to respond to reports that a bunch of disgruntled über-lefty teachers (are there any other kind?) have written a letter alleging that, as a seventeen year old schoolboy, Nigel Farage was a racist, a fascist and sung Hitler rally songs. This is just the type of ammunition that Cameron needs if he is to persuade the electorate not to vote for UKIP, so why the silence? Could it be, perhaps, that by publicly discussing alleged youthful indiscretions, the Prime Minister realises he might open up a can of worms he would prefer remained unopened?